<!doctype html public "-//w3c//dtd html 4.0 transitional//en"> <html> <body bgcolor="#FFFFFF">     <blockquote TYPE=CITE> <blockquote dir=ltr style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px"> Would you feel the same if the SB and ribs were out of the piano, just sitting on a flat surface, crown up?  If you take the rim out of the picture, then it seems to me the ribs don't support crown, unless they have a strong "spring" action in trying to straighten themselves.  Would you agree?</blockquote> </blockquote> This is that other analogy that just isnt quite right. To begin with, the ribs are not primarilly trying to straighten themselves. Primarilly they are resisting panel expansion. The "straighten themselves" perspective ignores the fact that pressing downwards on the panel increases the panels tendancy to expand... which is exactly the thing the ribs primarilly resist. It is this resistance to the panels expansion that causes crown to begin with. (opposite and equal way of saying its the panels compression that causes crown). This resistance just doesnt reverse itself and turn into a "flattening aid" simply because panel expansion is caused by a different source then taking on humidity. RicB       -- Richard Brekne RPT, N.P.T.F. UiB, Bergen, Norway <A HREF="mailto:rbrekne@broadpark.no">mailto:rbrekne@broadpark.no</A> <A HREF="http://home.broadpark.no/~rbrekne/ricmain.html">http://home.broadpark.no/~rbrekne/ricmain.html</A> <A HREF="http://www.hf.uib.no/grieg/personer/cv_RB.html">http://www.hf.uib.no/grieg/personer/cv_RB.html</A>   </body> </html>